Range finder



Oct. 13, 1936. J. WOODBURY 2,057,549

RANGE FINDER Filed May ll', 1935 Patented oet. 1s, i936 i 2,057,549

uni-Tao STATESPATENT orifice RANGE man.

John E. Woodbury, Worcester, Mass.

Application May 11, 1935, Serial No. 21,043

13 Claims. (Cl. 95-44) This invention relates to a range finder, parfinders are used which either read the distance ticularly adapted for camera work. in feet, or meters, or are placedso that the co- The principal objects of the invention are to ordination with the camera lens is complete. This provide a range finder supplying two points of type of range finder is arranged on a diiferent exact focus very accurately and thoroughly, afbasis than that stated above. 5 fording the operator a basis for precision work The range finder is shown as applied to an at certain distances and a basis for comparison ordinary type of camera i0 of the modern type for the securing of estimates at all other disin which the front Il snaps out instead of comtances; to provide ameans whereby a serviceable ing out on a track. The range finder body i3 valuable focusing aid of the greatest simplicity, preferablyis located in stationary position above 10 which is very easy to manufacture and get into the lens and on the front of the board. This is adjustment with a minimum danger of disorder, a Convenient place to locate the range iinder is obtained, capable of functioning at any time; but it can be located in other positions. At one to provide for directing a plurality of rays of side of the range flnderisa light deector, shown l5 light through the range finder which will not inas a mirror I4, arranged preferably at an angle 15 terfere with eachother and will permit of the of 45 degrees. At the opposite side of the range focusing of the camera at the two or more specic finder are two separate light defiectors, shown as distances for which it is constructed; to provide mirrors l5 and i6, arranged Defelbly hermeans for blinding or darkening either one of manently at 13W@ Separate angles at nearly 45 these rays of light so that each one can be used degrees. These mirrors could all he replaced by 2o separately without confusion; to provide a con 'prisms The ray Of light im the Obiecil passes struotion of range finder that can be p1aoed` in a through the clear space il in the mirror lf3 and convenient position on a, camera,involv'ing alight then through the prism m t0 produce e. Slight defiector, such as amirror or prism, broad enough angular deflection to the view ilnder lll. From to cover the two rays mentioned and having a the mirrors l5 and i6 two rays L' and Lz are 25 blank space between them so that blinders can reilected across the instrument to the mirror be arranged to shut off the light from either part i4 which is set at such an angle that the reflected of said deiiector; and to provide means connected ray L' meets L at exactly 6 feet. This gives the with the focusing of the lens for operating the effect of registration ofthe images seen through blinders at the proper time in accordance with I4 Iand i5 and i1 when the objet sighted is at 3g the turning of the'lens for getting the desired 6 feet. In a similar way the mirlm i515 Set focused distance. at such an angle to the mirror lll that the coincim Other objects and advantages of the invention dence of the light angle is at l5 feet, showing will appear hereinafter. exact registration at that point (see Fig. 2). In

3: Reference is to be had to the accompanying that figure the ray of light L passes through the 35 drawing, in whichmirror I4 because this mirror has its central por- Fig. 1 is a front view of a camera showing a tion scraped clear of silver atl Il for that purpose. preferred embodiment of this invention applied It will be seen that, in an instrument of this thereto; type, itis possible to detect immediately and with 4 Fig. 2 is a top view showing only the range accuracy two separate distances., The invention o finder and a little of the camera and illustrating is not limited to merely two but more mirrors can the rays of light; be used. Furthermore, it is obvious that the Fig. 3 is a sectional view, on the line 3--3 of 6 and l5 foot distances are not essential but Fig. 1, of the operating means for the range any plurality of distances can be chosen and the finder; focus will be made at those distances with great 45 Fig. 4 is a side view of the same taken in the cul direction of the arrow in Fig, 1; and It seems desirable to mount the prism i8 on Figs. 5 to 11 inclusive are views showing the the Side 0f the range nder t0 which the light is l images produced under different Conditions indirected from the object to the eye .for the purpose 5o cheating the darkened portions and the my or of turning the ray 0f light to about the angle 5o light. Each one shows shaded the mirrors 23 ShOWnin Fig- 2 S0 that the Overal/01', looking and 24 and unshaded the mirrors l5 and le. The Slightly downwardlyinto the range finder from. central portion'i'n each figure indicates the clear the edge 0f the Camera ai', 20. thrOugh a View portion in the mirror I4. finder I9, will be sighting in a direction parallel At the present time 'well known types o; range with the camera lens axis. Thus the camera may 55 be turned approximately to the proper direction totake the picture which is desired. This makes it easier to view the images involved and introduces no other difilculty.

A sight knob is mounted on the side of the camera which makes it easier to glance through the instrument without vmoving the eye very much from the position in which it is normally used on a direct vision view finder.

In the case illustrated the range finder has fitted into it, between the two sets of mirrors' or other light defiectors Il, I5 and I6, two shafts 2i and 22. These are fitted with small blades 23 and 24 of steel or other suitable non-light transmitting material serving as shutters or blinds. These blinds are fastened to the two shafts. The shafts are provided with two links 25 and 26 extending downwardly` in the present instance, which are connected with pivoted levers 21 and 28. `These levers have ends adapted to be engaged by cams 29, 30, 3i and 32 mounted on the usual focusing ring 33 by means of cam rings 34 and 35.

It is intended that this instrument should be fitted on the front of a camera of the modern type in which the focusing between 100 feet and the shortest distance that is likely to be used, as for example 6 feet, is accomplished by turning the focusing ring 33 of the lens one way or the other in a well known manner. Ths constitutes a ring which holds the lens. In the present case the amount of angular turn between 100 feet and 6 feet is assumed to be a very little less than three-quarters of a complete circle.

The support of the two links 25 and 26 and levers 21 and 26 is shown in Fig. 3.

YIiig. 4, as stated, shows a side view of the range finder and the two cam rings are clearly shown cooperating with the two levers, which are operated by them in such fashion that it is perfectly easy to see how the blinds 23 and 24 are actuated, as has been described.

The focusing ring 33 is fitted with two cam rings 34 and 36 fixed thereon. The ring 34 is mounted in front and has two cams 3i and 32. 'I'he ring 35 has two cams 29 and 36. These cams osciilate with their respective rings. When the lens is set at 100 feet both blinds 23 and 24 are closed. This gives the effect shown in Fig. 5 when the instrument is used in the manner intended. In this case there is no reflection through either mirror I5 or I6 from the mirror I4.

`If the camera lens is turned to such position that it is in focus, the cam rings 34 and 35 are turned with the lens and the cams 29, 30, 3| and 32 turn with them. When the lens has been turned around so that the focus is at 15 feet, the cam comes to the position in which the cam 29 is shown in Pig. l. This will result in closing the blind 23 whereas the blind 24 will be in a position to permit light to pass from the mirror I6 to the mirror I4. Consequently, the effect is that represented in Fig. 8, thus making it very easy to check accurate focus when the object is 15 feet away from the camera. If the object is at a different distance the result will be as shown in Fig. 9-, which clearly indic` .tes that the camera is not focused on the object at 15 feet.

In a similar way when the camera lens is set at 6 feet it will be found that the blind 24 closes off the mirror I6 and therefore, when the object.

It will be noticed that at all distances, other than 6, 15 and 100 feet, the range finder will be open in all three fields of vision, the direct light going through the clearcenter of the mirror I4 and both the mirrors I5 and IB, carrying their respective images in sight. The reason for this is that it depends only on the skill and ingenuity of the operator to be able to detect quite a wide variety of other distances by the degree of relative displacement of the three images. The most easily detected one of these relations is at about 9 feet where the effect gives the object in focus and the camera lens is set at 9 feet to show about as in Fig. 10,-where the displacement differences between the three images is about even. On the other hand. if any irreguiarityis seen and the result looks like Fig. 11, it will be known at once that it is not in focus unless very careful estimate between the focus and scale and the distance estimated is made.

It would seem at first sight that a range finder of this description, where three distances can be determined, two of which can be determined with extreme accuracy, and the third estimated with precision, is a very limited type of instrument as compared with the fully coordinated range finders which are the subject of several patents, including my own Patents Nos. 1,166,032, Dec. 28, 1915, 1,238,473 and 1,238,474 patented Aug. 28, i917. As a matter of fact, where the limitation might be estimated at a glance as, say,v70% deficient. the real fact is that this is not more than 15 or 25% deficient at the most. As one estimates, the difficulty is to correlate an accurate estimate to the general magnitude of one's surroundings. For instance, suppose that a careful attempt is made to estimate 6 feet and 15 feet in a small room. When this estimate is made outofdoors, where spaces are large, the estimate for 15 feet is too large. In other words, two yardsticks are carried, 6 feet and 15 feet, so that they can always be correlated to some object in the distance. This makes it possible to make accurate estimates under almost any conditions. It has been found quite easy to make estimates as used at least two or three times as accurately as can be made without the use of this instrument. The instrument comprises a comparatively small amount of mechanism and is much more cheaply manufactured than the range finders on the market and is almost impossible to. get out of order.

It will be understood, of course, that the distances 6 and 15 feet are selected arbitrarily but they are convenient distances. The mirrors can be set up orginally for other different distances and they will be shown with great exactness. The adjustment of the mirrors Il and I6, of course, is made when the instrument is manufactured but it can be made very simply and the danger of loss of adjustment is practically nothing. 'Ihe range finder can be used satisfactorily by a skilled operator and is in its moet elementary form for that purpose and yet this system lends itself very neatly to application to a conventional modern camera of the type in which the focusing is accomplished by the simple means of having a rotating lens mount operate the blinds and can be used satisfactorily by an amateur photographer with a very minimum chance of error in focusing.

It should be stated that when the camera is set at 100 feet both sides of the range finder should be darkened by the blinds and, in fact, it is preferred that at all other distances than 6 and 15 feet, for instance, the blinds should both be opened as a warning that some judgment must be used to secure a perfectly focused result.

The range finder can be secured on the camera in many ways but it seems most universally de sirable to have it put crosswise above the lens on the conventional hand camera. This puts it in a convenient position to be related to the turning lens and entirely out of the way of the holding mechanism which supports the lens board in the proper position.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what' I claim is:-

1. A range finder comprising a ray deflector, and a plurality of ray defiectors arranged to turn rays toward the first named ray deiiector, but at different angles.

2. A range finder comprising a ray deflector, a plurality of ray deiiectors arranged to turn rays toward the first named ray deflector, but at different angles, and means for shutting off the rays from any of the plurality of ray deflectors.

3. A range finder comprising a mirror. and a plurality of ray defiectors arranged to turn rays toward the mirror, but at different angles, the mirror having a clear space to allow direct rays of light to pass.

4. A range finder comprising a mirror set at about 45 degrees to a ray of light directed toward the camera and having a clear space at the center, and two mirrors about parallel to the first mirror but at aslight angle to each other, and each arranged to cooperate with one part of the first mirror independently.

5. A range finder comprising a mir'ror set at an angle to a ray of light directed toward the camera and having a clear space at the center, two mirrors about parallel to the first mirror but at a slight angle to each other, each arranged to cooperate with one side of the mirror. and blinds for closing oif the rays from each of said two mirrors to the first named mirror.

6. A range finder comprising a mirror set at about 45 degrees to a ray of light directed toward the camera and having a clear space at the center, two mirrors about parallel to the first mirror but at a slight ,angle to each other, each arranged to cooperate with one side of the first mirror, blinds for closing od the rays from each of said two mirrors to the first named mirror, and means for operating said blinds independently.

'1. In a range finder of a type suitable for use on a camera, the combination with a camera, of a ray defiector constructed to pass some of the rays directly, and a plurality of ray defiectors at different exact angles to the first ray deflector, whereby the exact measurement of the plurality of distances corresponding to the angles of the second set of deflectors can be made.

8. In a camera of the focusing type, the com-l bination of a rotatable lens, a lens mount mounted to rotate therewith, ray deiiectors, blinds arranged to close off the rays of light to certain of said ray deflectors. and means movable with the lens mount for operating saidv blinds.

9. In a camera of the focusing type, the combination of a rotatable lens mount, a mirror set at an angle in the line of a' ray of light coming from the object being focused to the eye of the operator and having a clear spacel a pair of mirrors set at nearly the angle of the first mirror but at slightly different angles for reflecting rays of light to the first mirror, blinds for obstructing the iight from one mirror to another, and

cams carried by the lens mount for closing said blinds. i

l0. The combination of a hand camera of the focusing type, with a range finder for the purpose of focusing, said range nder comprising a plurality of mirrors, each in fixed relation to the others, one of said mirrors being adapted to receive rays from either one of the others so that the mirrors cooperate in different pairs to establish accurately 'a certain distance of focus for each pair.

1l. The combination of a hand camera of the focusing type with a range finder for the purpose of focusing, comprising a. plurality of sets of ray deflectors arranged to deflect the rays of light at different angles, means for automatically permitting different sets of ray deflectors to be viewed when the lens of the camera is focused on dierent distances related to the exact angle between the respective sets of deflectors.

l2. In a camera of the focusing type, the combination with the apparatus for focusing, of a lens, blinds for shutting oif the rays of light through the focusing apparatus, and means cooperating with the focusing apparatus and the blindsv for coordinating the operation of the lens with the effects of the focusing apparatus.

13. A range finder comprising a view finder and two ray deiiecting surfaces having a clear. 

